Methods, apparatuses and systems directed to a wireless network interface supporting directional antenna diversity. directional diversity, in one embodiment, makes use of antennas with higher gain and non-overlapping patterns to provide communication over a greater area and select the best antenna to receive signals transmitting wireless frames or packets. Certain embodiments optimize wireless network systems using orthogonal frequency division multiplexed (OFDM) signals where spatial diversity protection provided by spatially-separated, omni-directional antennas is not required. In other embodiments, use and selection of directional antennas allows for sectorization resulting in performance gains such as extended coverage areas, noise reduction, enhanced efficiency, and increased throughput.
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15. In a wireless network system comprising a plurality of directional antennas oriented about an axis, wherein the plurality of directional antennas have substantially non-overlapping patterns relative to each other, and wherein the peak gains of the antennas are oriented radially and outwardly about the axis and offset relative to each other at an angle substantially equal to 360/N, where N is the number of directional antennas in the plurality of directional antennas, a method comprising
detecting a signal transduced by one of the directional antennas, wherein the signal transmits a wireless frame, the wireless frame including a preamble;
during receipt of the preamble of the frame, selecting one from the plurality of the directional antennas based on at least one attribute of the respective signals transduced by the antennas;
switching to the selected directional antenna for receipt of the remainder of the frame.
20. An apparatus for enhancing operation of wireless network environment, comprising
a plurality of directional antennas oriented about an axis, wherein the plurality of directional antennas have substantially non-overlapping patterns relative to each other, and wherein the peak gains of the plurality of antennas are oriented radially and outwardly about the axis and offset relative to each other at an angle substantially equal to 360/N, where N is the number of directional antennas in the plurality of directional antennas;
a switch operatively connected to the plurality of antennas and operative to switch between the antennas in response to control signals;
a detector operative to detect at least one signal attribute of the signals transduced the antennas; and
an antenna selection module operative, during receipt of the preamble of a wireless frame, to
provide control signals to the switch designating a selected antenna,
evaluate signal attributes provided by the detector,
select an antenna from the plurality of antennas for receiving the signal associated with the wireless frame; and
an orthogonal frequency division multiplexed (OFDM) module operative to
receive the signal from the switch,
and recover a digital data stream from the signal.
1. An apparatus for enhancing operation of wireless network environment, comprising
a plurality of directional antennas oriented about an axis, wherein the plurality of directional antennas have substantially non-overlapping patterns relative to each other, wherein the peak gains of the plurality of directional antennas are oriented radially and outwardly about the axis and offset relative to each other at an angle substantially equal to 360/N, where N is the number of directional antennas in the plurality of directional antennas; wherein the plurality of directional antennas are each operative to transduce a radio frequency signal and provide an output signal corresponding to the radio frequency signal;
a switch operatively connected to the plurality of antennas and operative to switch between the antennas in response to control signals;
a detector operative to detect at least one signal attribute of the output signals provided by the directional antennas; and
an antenna selection module operative, during receipt of the preamble of a wireless frame, to
provide control signals to the switch designating selected directional antennas in the plurality of directional antennas,
evaluate the respective output signals provided by the selected antennas, and
select a directional antenna from the plurality of directional antennas for receiving the radio frequency signal associated with the wireless frame.
2. The apparatus of
3. The apparatus of
4. The apparatus of
5. The apparatus of
6. The apparatus of
compose a frame for transmission to a destination,
retrieve the antenna identifier associated with the destination address in the data structure,
transmit control signals to the switch designating the retrieved antenna for use in transmitting the composed frame.
7. The apparatus of
8. The apparatus of
12. The apparatus of
13. The apparatus of
14. The apparatus of
16. The method of
demodulating the signal to provide a digital data stream,
recovering a data packet from the digital data stream.
17. The method of
transmitting an acknowledgement frame using the selected directional antenna.
19. The method of
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This application makes reference to the following commonly owned U.S. patent applications and patents, which are incorporated herein by reference in their entirety for all purposes:
U.S. patent application Ser. No. 10/155,938 in the name of Patrice R. Calhoun, Robert B. O'Hara, Jr. and Robert J. Friday, entitled “Method and System for Hierarchical Processing of Protocol Information in a Wireless LAN;” and
U.S. patent application Ser. No. 10/407,357 in the name of Patrice R. Calhoun, Robert B. O'Hara, Jr. and Robert J. Friday, entitled “Method and System for Hierarchical Processing of Protocol Information in a Wireless LAN.”
The present invention relates to wireless signals and, more particularly, to methods, apparatuses and systems directed to non-overlapping antenna pattern diversity in wireless network environments.
A wireless Local Area Network is a wireless communication system with radios having relatively high throughput and short coverage ranges. Many wireless LANs are based on iterations of the IEEE 802.11 standard. Radio signals passing between a transmitter and a receiver in an indoor environment are reflected from many surfaces of objects in that environment. This results in the radio signal following many different paths between the transmitter and receiver. This phenomenon is called “multipath.”
When the coherence bandwidth of the RF channel is on the same order as the signal bandwidth of the signal, multipath in a radio system using most narrow-band or spread spectrum communication techniques results in interference at the receiver that must be addressed. This interference is a result of the radio receiver performing a vector addition of all the signals received from all of the various paths they follow between the transmitter and receiver. This vector addition can result in a very weak resultant signal (destructive interference) or a strong resultant signal (constructive interference).
Whether the resultant signal detected at the receiver is affected by destructive or constructive interference is a function of the relative positions of the transmitter, receiver, and all other objects that reflect the radio signal along paths between the transmitter and receiver. Because the spatial relationship between all these objects is the determining factor in the result of the vector addition of the received signals, moving the transmitter or receiver by a small amount (on the order of a wave length) will have a significant effect on the resultant signal.
For modulation methods based on modulating a single carrier, spatial diversity takes advantage of this characteristic (i.e., that moving one antenna a small distance can have a great effect on the resultant received signal), by separating two or more antennae by a wavelength or more and sampling the received signal at each antenna, before choosing one of the antennae to be used for reception. This spatial diversity technique uses antennae with patterns (coverage areas) that are typically similar and overlapping. If the patterns did not overlap, the effect of using the antennae for spatial diversity would be reduced. Recently, techniques other than single carrier modulation have been used for radio WLAN communication. Specifically, Orthogonal Frequency Division Multiplexing (OFDM) has been utilized. OFDM is a broad-band communication mechanism that addresses the multipath issue in the design of the modulated signal itself. Therefore, spatial diversity has diminished utility with this type of radio signal.
Despite the use of OFDM, the need remains for further optimizing signal reception between transmitters and receivers. For example, a need in the art exists for increasing the coverage area of the radios associated with access points to enable reductions in the number of access points required to adequately implement a wireless network environment. A need also exists for maintaining user performance, network efficiency, and data throughput under increased user load in a wireless network environment. Embodiments of the present invention substantially fulfill these needs.
The present invention provides methods, apparatuses and systems directed to a wireless network interface supporting directional antenna diversity. Directional diversity, in one embodiment, makes use of antennas with higher gain and non-overlapping patterns to provide communication over a greater area and select the best antenna to receive signals transmitting wireless frames or packets. Certain embodiments optimize wireless network systems using Orthogonal Frequency Division Multiplexed (OFDM) signals where spatial diversity protection provided by spatially-separated, omni-directional antennas is not required. In other embodiments, use and selection of directional antennas allows for sectorization resulting in performance gains such as extended coverage areas, noise reduction, enhanced efficiency, and increased throughput.
In one embodiment, the wireless network interface unit can be incorporated into wireless network access points, such as access points 12, 14, 15, and 16 shown in
Antenna selector 20 is operative to receive signals transduced by antennas 12a, 12b, select an antenna based on detected signal attributes associated with the antennas, and provide the signal corresponding to the selected antenna to radio module 30. Antennas 12a, 12b are directional antennas having non-overlapping patterns. Although the various Figures show two antennas, the present invention can operate in conjunction with more than two directional antennas having substantially non-overlapping patterns. Antennas 12a, 12b can be any suitable directional antennas, such as patch antennas, yagi antennas, parabolic and dish antennas. In one embodiment, the peak gains of the antennas are offset from one another in a manner that maximizes coverage in all directions. In one embodiment, the peak gains of the antennas are oriented relative to each other at an angle A about the vertical or z-axis, where A is equal to 360/n degrees±10 degrees (where n is the number of antennas). Accordingly, for a two-antenna system (see
As
Detector 26 can detect one to a plurality of signal attributes, such as signal strength, signal-to-noise ratio, etc. In one embodiment, the functionality of detector 26 is embodied within an integrated circuit. One skilled in the art will recognize that such signal attribute detection functionality is part of standard 802.11 wireless chip sets. As to signal strength, the detector 26 can provide absolute signal strength values, such as decibels (dBs) or relative indicators, such as RSSI values.
Antenna selection module 24, during the preliminary or preamble portion of the signal, evaluates the signals received at each antenna, such as antenna 12a and 12b, and selects an antenna for receipt of the remaining signal data corresponding to the wireless packet or frame. For example, according to the 802.11 protocol, MAC sublayer data units are mapped into a framing format suitable for wireless transmission. The MAC sublayer data units, according to the 802.11 protocol, are essentially encapsulated by a PLCP preamble and a PLCP header, thereby forming a PLCP protocol data unit (PPDU). The PLCP header generally includes a SYNC field and Start Frame Delimiter (SFD). The SYNC field allows the receiver to perform necessary operations for synchronization, while the SFD indicates the start of PHY-dependent parameters in the PLCP header. According to the 802.11 protocol, once the signal associated with the synchronization field is detected, the PHY layer functionality of the receiver searches for the SFD to begin processing the PHY-dependent parameters in the PLCP header. In one embodiment, during receipt of the preamble, antenna selection module 24 evaluates the signals transduced by antennas 12a, 12b (as provided by detector 26) and selects an antenna based on the detected signal attributes. The selected antenna is the used to receive the signal for the remainder of the PPDU. In one embodiment, the acknowledgment (ACK) frame is transmitted from the same antenna originally selected to receive the signal from the wireless station.
In one embodiment, the antenna selection module 24 provides the identifier corresponding to the selected antenna to radio module 30 or MAC control unit 40 (112). MAC control unit 40 can then store the selected antenna identifier and the MAC address in a table or other suitable data structure. In one embodiment, the identifier corresponding to the selected antenna is later stored in association with the MAC address of the source transmitter or wireless client. As discussed below, this is used, in one embodiment, to select an antenna for transmission of frames to the wireless client.
As
If the frame is a multicast or broadcast frame, such as a Beacon Frame, in one embodiment, a default antenna is selected (205) and used to transmit the frame. As
Other embodiments of antenna selector are possible.
The invention has been explained with reference to specific embodiments. Other embodiments will be evident to those of ordinary skill in the art. For example, the antenna selection functionality according to the present invention can be incorporated into wireless clients in addition to access points, assuming the wireless clients are equipped with more than one directional antenna. It is, therefore, intended that the claims set forth below not be limited to the embodiments described above.
Patent | Priority | Assignee | Title |
11469740, | Dec 09 2013 | Shure Acquisition Holdings, Inc. | Adaptive self-tunable antenna system and method |
7200421, | Oct 20 2003 | Kyocera Corporation | Base station device achieving effective use of frequencies by changing structures of antennas |
7444240, | May 20 2004 | Ford Global Technologies, LLC | Collision avoidance system having GPS enhanced with OFDM transceivers |
7542750, | Jun 17 2004 | Harman Becker Automotive Systems GmbH | Diversity system with identification and evaluation of antenna properties |
7652634, | Sep 01 2005 | Dell Products L.P. | Antenna with integrated parameter storage |
7652635, | Sep 01 2005 | Dell Products L.P. | Antenna with integrated parameter storage |
7916690, | Nov 05 2004 | Cisco Systems, Inc. | Graphical display of status information in a wireless network management system |
8483762, | Mar 07 2003 | Apple Inc | Method and apparatus for enhancing link range in a wireless network using a self-configurable antenna |
8570941, | Jun 09 2008 | Qualcomm Incorporated | Methods and apparatus for facilitating network-based control of a forwarding policy used by a mobile node |
9083074, | Apr 09 2012 | Malikie Innovations Limited | Dynamic antenna selection based on user hand position |
Patent | Priority | Assignee | Title |
5945954, | Jan 16 1998 | Tyco Electronics Logistics AG | Antenna assembly for telecommunication devices |
6085076, | Apr 07 1997 | XIRCOM WIRELESS, INC | Antenna diversity for wireless communication system |
6215447, | Jan 16 1998 | Tyco Electronics Logistics AG | Antenna assembly for communications devices |
6335704, | Mar 31 2000 | Mitsubishi Denki Kabushiki Kaisha | Antenna device |
6473040, | Mar 31 2000 | Mitsubishi Denki Kabushiki Kaisha | Patch antenna array with isolated elements |
6768457, | Mar 02 2001 | Delphi Delco Electronics Europe GmbH | Diversity systems for receiving digital terrestrial and/or satellite radio signals for motor vehicles |
20030095074, | |||
20030137468, |
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